Prime Minister Narendra Modi on Thursday paid heartfelt tributes to Britain's Queen Elizabeth II, saying she was a stalwart who provided inspiring leadership to her nation and people.

She personified dignity and decency in public life, Modi said, recalling his "memorable" meetings with the Queen in 2015 and 2018.

"I will never forget her warmth and kindness. During one of the meetings she showed me the handkerchief Mahatma Gandhi gifted her on her wedding. I will always cherish that gesture," the prime minister said.

"Her Majesty Queen Elizabeth II will be remembered as a stalwart of our times. She provided inspiring leadership to her nation and people. She personified dignity and decency in public life. Pained by her demise. My thoughts are with her family and people of UK in this sad hour," he said.

Queen Elizabeth II, the UK's longest-serving monarch, died on Thursday at Balmoral Castle in Scotland after reigning for 70 years. She was 96.